Method of making a lignocellulose product



NIETHOD OF MAKING A LIGNOCELLULOSE PRODUCT Arthur E. Gabriel, Ocean Grove, N.J., assignor to Caradco Incorporated, a corporation of Iowa No Drawing. Original application May 4, 1955. Ser.

No. 506,091, now Patent No 2,855,320, dated Oct. 7,

1958. Divided and this application July 16, 1958, Ser. No. 74f8,785

Claims. (Cl. 260-124) This invention relates to methods of making a lignocellulose product and the products resulting therefrom.

This application is a division of my co-pending application, Serial No. 506,091, filed May 4, 1955, now Patent 2,855,320, issued October 7, 1958.

One of the objects of this invention is to provide an im proved method of making a lignocellulose product consisting essentially of intimately mixing particles of lignocellulose material with an activator that is either iron sulfate and silica gel or iron sulfate and calcium carbonate and lignin, and heating said mixture under pressure for a time and at -a temperature sufficient to combine chemically at least a major portion of said activator with said lignocellulose.

Another object of the invention is to provide an improved method of making a lignocellulose product consisting essentially of intimately mixing particles of lignocellulose material with up to about by weight of an activator that is either iron sulfate and silica gel or iron sulfate and calcium carbonate and lignin, and heating said mixture under pressure for between about 0.1-60 minutes at between about 400-700 F. during at least a portion of the heating period to combine chemically at least a major portion of said activator with said lignocellulose.

Other objects and advantages of the invention will be readily apparent from the following detailed description of the invention.

In general, the method of this invention involves mixing finely divided lignocellulose with the above-mentioned activator to form a substantially homogeneous mixture which is then heated to combine chemically at least a portion of the activator and the lignocellulose. Where the mixture is given a preliminary heat treatment, the product is a thermoplastic molding composition capable of being molded under pressure and heat to produce a product having the shape of the mold cavity.

The preheat product may be stored if desired and then later molded under heat and pressure in a mold of suitable shape to produce articles as described above.

It has long been known that lignocellulose particles such as finely divided wood can be compressed into a coherent mass by heat and pressure as the heat apparently causes the lignin to become plastic and serve as a binder. The temperatures required, however, are so high that they cause rapid and almost spontaneous decomposition of the lignocellulose so that this method is not practical. The methods of this invention greatly minimize such decomposition so that a plastic mass is produced that can easily be molded under pressure.

The lignocellulose used is preferably relatively dry and in the preferred process does not contain over about of water by weight of the dry lignocellulose, which is approximately the fiber saturation point.

The lignocellulose that may be used includes wood and lignocellulosic vegetable materials as well as partially hydrolyzed or pulped lignocellulose. In order to insure Patented Dec. 13, 1960 intimate contact of the materials, the lignocellulose is preferably finely divided, with the particles preferably being not coarser than an average of about 20 mesh although an average of 50 mesh particles produces a smoother, stronger and finer-grained final product.

The amount of each ingredient in the mixtures of iron sulfate plus silica gel and of iron sulfate plus calcium carbonate plus lignin is preferably not less than about 0.3% by weight.

The particle size of each chemical compound should be small in order to insure even distribution of the compound throughout the mass and to bring the compound into intimate contact with the particles of lignocellulose.

In general, this particle size is preferably not coarser than about 50 to mesh, and is preferably not finer than 200 or 300 mesh. This means that the compound used has an average particle size passing through standard screens of these sizes.

In preparing the products of this invention, the lignocellulose material and the activator are intimately mixed to produce a substantially homogeneous mass. This mixture is then preferably compacted so that during the subsequent heating step relatively good heat transfer is achieved. The mixture may then be given an initial heating or preheat, either under no pressure or light pressure, in order to combine chemically a portion of the activator with the lignocellulose material. This initial heat treatment where employed makes the resulting product'relatively thermoplastic for subsequent molding operations. The preheat temperature is relatively high in order to drive ofi vapors and to cause the chemical combination of at least a portion of the chemical compound or mixture. However, the preheat temperature is maintained low enough so that excessive charring is avoided and high boiling compounds are not lost.

The product of this preheat treatment is a molding composition that is capable of being molded under pressure and heat in a mold of desired shape to produce molded products. This molding composition is a mixture of substantially dry lignocellulose with some chemically reacted lignocellulose substantially uniformly distributed therebrief period at a desired pressure and heated at a tempera- 1 ture which may be somewhat lower than the preheat temperature if desired, but which may be'substantially the same as the preheat temperature, if desired. In the preferred method this molding temperature will be between about 250 to 700 F. The time of moldingis such that the total time, including the preheat time if a preheat is used, is between about 0.1 to 60 minutes.

The pressure that is employed is governed by the desired characteristics in the final product. In general, this pressure will be between about 50 and 5,000 pounds per square inch, although higher and lower pressures may be employed, depending upon the desired characteristics of the final product. At the lower pressures, the product will be found to be relatively low in density and relatively porous. At the higher pressures the product is hard, dense and compact and more nearly resembles molded thermosetting resins.

In the final molding operation the pressure is maintained during the heating operation for a time suflicient to set the mixture. As is pointed out above, the total heating including the preheat and the final molding operation is'preferably between about 0.1 to 60 minutes. I

In the following table there is set out a number of examples of producing products according to this invention; The first column of the table sets out the example number. The second column identifies the particular activator or chemical compound or mixture employed, while the third column sets out the amount" of activator and percentage by Weight. The fourth column gives the temperature of both the preheat and the final molding, While the fifth column gives the preheat time in minutes, except where otherwise indicated, for the preheating step, Where no preheat is used in any example, this titrie is indicated aS ifQfi" The final column gives 'the molding time in minutes in the final molding step. t In each eigample, finely dividediponderosa pine wood having a maximurn 'particles size'offabout 50 mesh and substantially bone drywas mixed with the stated amount or the specified activator. The wood. and. the activator were intimately mixed to produce a substantially homogeneous product. A mass of this mixture about.1% inches'thiek was then partially compacted into a square mold: frame about oneinch deep. The mixture rested on a fine mesh wire screen which was supported on a metal plate. The plate, screen and frame had been preheated to the specified temperature. A preheated metal top plate" and block were then placed on the mold with the mixture therein placed on a heated platen of. a press. The mixture within the mold was compacted. to a pressure of about 40.0 pounds per square inch in'order to increase the efliciency ofheat transfer through the mass and this pressure then removed. The heated platen was maintained at a'temperature such as to heat the mixture to the specified temperature and this temperature was mainainedl' for the specified pr'eheat 'ame'." The screen aided inventing the gases givenfotf during this preheat.

At the end of the preheatpejriod, the partially rel st, a qm a tsi sfus il he e platens-f th'e 'pressfor the specified'iin'oldingftime at the particular tempera re given. At the 'iidibf thistime perio d, the pr: surewas released and' th'e 'finishedf product removed m lf esl .5999. Wh9t..' srhsst. mp o ed. the i e, 994 l nai. st yat'shwas p ace d ect y i the and heated .at' the specifiedtemperature and at.

a pressure of 700poun'ds, per square inch for the molding-time given inthe last column of the table. The mo1ding time is in minutes unless otherwise stated. 0 i

as as... as... "W-

E nNo Activator cent F time time? .5. by wt; (min.)} (min.)

Per- Temp., Preheat Molding Ex. No. Activator cent F. time time by wt. (min.) (min.)

Having, described myv invention as related to the em-v bodimentset out herein, it is my intention that the invention'oe not limited by any. of the details of description unless. otherwise specified, but rather be construed broadlywithin itsv spirit and, scope as set outinv the accompanying claims.

I claim:

l, The method. of making a lignocellulose product, consisting essentially of: intimately mixing particles of lignocellulosewithup to about 20%, by weight of an activator of the. class consisting of iron sulfate plussilica gelandimu sulfateplus calcium carbonate plus lignin, each. ingredient of. said class beingin anamount of at least 0.3 by weight; and heatingthe resultingcomposition under pressurefor a time and at a temperature su tficient to combine chemically a major. portion ofthe activator with the lignocelluose- 2. The method of claim 1 wherein said activator consists essentially of iron sulfate plus silica gel.

3.- The method of claim 1 wherein. said; activator. con sists essentially of iron sulfate plus calcium carbonate plus lignin.

4; The method of making a lignocellulose product, consisting essentiallybf; intimately mixingparticlesot lignocellulose with up to about 20% by weight of an activator of the class consisting of iron sulfate plus silica geland iron sulfate plus calcium carbonate plus lignin, eaching'redient of said class being in an amountof at least10.3%i by Weight; and heating the resulting composition under pressure for between about 0.1 -60minutes. and at between about 400700 F. to combine chemically a major portion of .the activator with the lignocellulose.

5. The method ofclainrAwhereinsaid activator consists. essentially ofiron-sulfateplus silicagel.

The method of claim 4.wh erein said activatorconsistsl essentially, of ciron sulfate 1 plus calcium carbonate plu'sflignimj 7. The thermal reaction productofa mixture of finelydivided.lignocellulose and up to. about" 20%. by weight of an activatorof the., class consisting offiron sulfate plussilica .gel and iron sulfate plus calcium. carbonate plus lignin, each ingredient of said class. being in anamount of at least 0.3% by weight.

8. The thermal reaction product of a mixture of finelyivid d li a'ocel u sse. n 1 9. Q bQut 0%,- Y ei ht f l ctiv to of the ls swns sti o rqnsul a e Plu silica gel and iron sulfate plus calciurn carbonate plus said clas s being in an amount of at, least 0.3% by weight.

9. The thermal reaction product of a mixture of finelydivided ligno'cellulose and up to a total of about 20% by each in an amount of at least 0.3% by weight, the mix weight of iron sulfate plus silica gel, each in an amount ture having been heated to between about 400-700 F. of at least 0.3% by weight, the mixture having been fo between about 0.1-60 minutes.

heated to between about 400700 F. for between about l-g T i l zg 1 t d t f t f fi I 5 References Cited in the file of this patent e erma reac 1on pro no 0 amlx ure O ne ydivided lignocellulose and up to a total of about 20% by UNITED STATES PATENTS weight of iron sulfate plus calcium carbonate plus lignin, 2,855,320 Gabriel Oct. 7, 1958 

1. THE METHOD OF MAKING A LIGNOCELLULOSE PRODUCT, CONSISTING ESSENTIALLY OF: INTIMATELY MIXING PARTICLES OF LIGNOCELLULOSE WITH UP TO ABOUT 20% BY WEIGHT OF AN ACTIVATOR OF THE CLASS CONSISTING OF IRON SULFATE PLUS SILICA GEL AND IRON SULFATE PLUS CALCIUM CARBONATE PLUS SILICA EACH INGREDIENT OF SAID CLASS BEING IN AN AMOUNT OF AT LEAST 0.3% BY WEIGHT, AND HEATING THE RESULTING COMPOSITION UNDER PRESSURE FOR A TIME AND AT A TEMPERATURE SUFFICIENT TO COMBINE CHEMICALLY A MAJOR PORTION OF THE ACTIVATOR WITH THE LIGNOCELLULOSE.
 7. THE THERMAL REACTION PRODUCT OF A MIXTURE OF FINELYDIVIDED LIGNOCELLULOSE AND UP TO ABOUT 20% BY WEIGHT OF AN ACTIVATOR OF THE CLASS CONSISTING OF IRON SULFATE PLUS SILICA GEL AND IRON SULFATE PLUS CALCIUM CARBONATE PLUS LIGNIN, EACH INGREDIENT OF SAID CLASS BEING IN AN AMOUNT OF AT LEAST 0.3% BY WEIGHT. 